Content-aggregation websites, including social-networking websites, often display content to a user using graphical user interface (GUI) functionality called a “content stream”. Such websites determine inclusion or prominence of an item (e.g., an article) in the content stream based at least in part on the a personalized user-interest profile which records the user's explicit (e.g., expressly identified interests) and implicit relevance feedback (e.g., clicks) as to previous items of content presented in the content stream.
However, the personalized user-interest profile for an infrequent user might be nearly empty. Consequently research into such profiles remains an active area of research and experimentation.